period 3 Flashcards
appearance and physical properties of sodium
metallic, shiny, conducts electricity (worst conductor out of the metals)
reaction of sodium with acid
Na + acid –> H2 + salt
reaction of sodium with cold water - equation and observations
vigorous reaction, floats on water, fizzes, melts due to negative change in H
NaOH is pH 13-14
2Na + 2H2O –> 2NaOH + H2
reaction of sodium with oxygen
(equation and observations)
bright yellow flame, forms white powder of Na2O
2Na + 1/2O2 –> Na2O
appearance and physical properties of magnesium
metallic, shiny, conducts electricity (between Na and Al in terms of how well it conducts)
reaction of Mg with cold water
(observations and equation)
very slow reaction
pH = 10 as Mg(OH)2 is sparingly soluble
Mg + 2H2O –> H2 + Mg(OH)2
reaction of Mg with steam (observations and equation)
much faster than with water
Mg + H2O –> MgO + H2
reaction of Mg with oxygen
(observations and equation)
bright white flame, forms white powder of MgO
2Mg + O2 –> 2MgO
appearance and physical properties of aluminium
metallic, shiny, best conductor of electricity in period 3
reaction of Al with cold water
no reaction
reaction of Al with oxygen (equation and observations)
heat and lower into jar of O2 –> bright flame, forms white powder
4Al + 3O2 –> 2Al2O3
reaction of Al with oxygen (equation and observations)
heat and lower into jar of O2 –> bright flame, forms white powder
4Al + 3O2 –> 2Al2O3
reaction of Al with oxygen (equation and observations)
heat and lower into jar of O2 –> bright flame, forms white powder
4Al + 3O2 –> 2Al2O3
why is aluminium considered unreactive even though the metal itself is reactive
covered by Al2O3 from where oxygen has oxidised the surface of the Al
Al2O3 is unreactive - makes it useful for saucepans, window frames etc.
if Al2O3 is scratched off, Al reacts rapidly with air to form a new coat
appearance and physical properties of silicon
semimetal (metalloid), semiconductor (conducts electricity to an extent and in certain conditions
reaction of silicon with oxygen (observations and equation)
heat strongly
Si + O2 –> SiO2 (white powder)
appearance and properties of phosphorous
non-metal
low mp and bp
doesnt conduct electricity
red phosphorous has a crystal structure
white phosphorous as P4
reaction of phosphorous in excess oxygen (observations and equation)
Red P needs to be heated significantly first, white P ignites spontaneously in air
Phosphorous pentoxide (white crystalline solid) formed
4P + 5O2 –> P4O10
reaction of P in limited oxygen
incomplete combustion: colourless liquid phosphorous trioxide is formed
4P + 3O2 –> P4O6
appearance and physical properties of sulfur
non-metal
low mp and bp
does not conduct electricity
reaction of sulfur with oxygen (observations and equations)
need to heat and lower into a jar of oxygen
colourless gas sulfur dioxide formed
some SO3 also formed
S + O2 –> SO2
what structure and bonding in Na and Mg oxides
ionic lattice
structure and bonding in Al oxide
ionic lattice with covalent character, Al3 + distorts O2 electron cloud
structure and bonding in Si oxide
giant covalent
structure and bonding in P and S oxides
simple molecular covalent
what is the trend in melting points for period 3 oxides (state highest and lowest and why)
highest is MgO and lowest is SO2
increases along group for metals Na2O and MgO due to stronger ionic bonding, but Al2O3 is lower due to the covalent character of the bonding.
decreases with size for simple molecular molecules
which period 3 oxides are basic
Na2O and MgO
reaction of Na oxide with water? pH?
Na2O + H2O –> 2Na+ + 2OH-
pH = 14
reaction of Mg oxide with water? pH?
MgO + H2O –> Mg2+ + 2OH- <—> Mg(OH)2
pH = 9-10 as Mg(OH)2 is sparingly soluble
what are the products if Na2O and MgO are reacted with acid
salt and water only
is aluminium oxide acidic or basic
amphoteric
act as either
is aluminium oxide soluble
not in water
reaction of aluminium oxide with HCl
Al2O3 + 6HCl –> 3H2O + 2AlCl3
reaction of aluminium oxide with NaOH
Al2O3 + 2NaOH + 3H2O –> 2NaAl(OH)4
sodium aluminate is formed
is silicon dioxide soluble in water
no
in what conditions will silicon dioxide act as an acid
reacts as a weak acid with a strong base (e.g. hot, concentrated NaOH)
reaction of silicon dioxide with hot, concentrated NaOH
SiO2 + 2NaOH –> H2O + Na2SiO3
sodium silicate formed
how is silicon dioxide used in production of Fe
SiO2 + CaO –> CaSiO3
calcium silicate
reaction of phosphorous pentoxide with water? pH?
P4O10 + 6H2O –> 4H3PO4
pH = 1-2
dissociation of the acid formed (H3PO4)
H3PO4 –> H+ + H2PO4-
reaction of P4O10 with NaOH
3NaOH + H3PO4 –> Na3PO4 + 3H2O
reaction of P4O10 with NaOH
3NaOH + H3PO4 –> Na3PO4 + 3H2O
reaction of SO2 with water? pH?
SO2 + H2O –> H2SO3
weak acid pH = 2-3
reaction of SO3 with water? pH?
SO3 + H2O –> H2SO4
strong acid pH = 0-1
reaction of SO2 with NaOH
SO2 + NaOH –> NaHSO3
NaHSO3 + NaOH –> Na2SO3 + H2O
how can flue gases be removed by CaO
CaO + SO2 –> CaSO3
(calcium sulfite)
how many electrons does P have in its outer shell in H3PO4
10
what is the shape and bonding in PO4 3-
electrons delocalise to give tetrahedral structure with 109.5 bond angle
each P-O bond is the same length
what is the structure, bonding and shape of SO4 2-
electrons delocalise –> tetrahedral with 109.5 bond angle
each S-O bond is the same
what is the structure, bonding and shape of SO3 2-
bond angle = 106
each S-O bond is the same
S has one lone pair of electrons
uses of MgO
additive for cattle feed
how useful is Al2O3
oxide layer on aluminium makes it very useful as it is unreactive and returns quickly if it is scratched off
uses of SO2
reactant in contact process (making H2SO4)
would lithium oxide or sodium oxide have a higher melting point
Li2O has a higher mp since Li+ is a smaller ion than Na+, so the O2- and Li+ charge centres are closer together and there is a greater electrostatic force of attraction between the oppositely charged ions
